


Size Up

by assholemurphamy



Series: Touch Me (I Wanna Be Dirty) [1]
Category: Supernatural
Genre: Alternate Universe - Canon Divergence, Anal Sex, Bottom Sam, Cock Slut Sam, Dirty Talk, Incest, M/M, Masturbation, Non-Canon Relationship, Sibling Incest, Size Kink, Size Queen Sam, Slut Sam, Smut, Top Dean, Wincest - Freeform, dean has a huge cock, pre S1
Language: English
Status: Completed
Published: 2016-09-29
Updated: 2016-09-29
Packaged: 2018-08-18 11:06:01
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,399
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8159974
Author URL: https://archiveofourown.org/users/assholemurphamy/pseuds/assholemurphamy
Summary: "Have you ever fucked someone that big, baby brother?"~or~Dean gets out of the shower to find his little brother fingering himself to size queen porn. 
Sam has never taken a cock so large before.Dean has yet to find someone capable of taking his cock all the way.





	

**Author's Note:**

> Prompt Fill for this prompt -  
> http://assholemurphamy.tumblr.com/post/151082447622/ao3-prompt-wincest-size-kink-pleeeaseee-bottom  
> (idk how to code, so sorry)
> 
> "AO3 prompt- Wincest size kink pleeeaseee. bottom sam, top dean. if possible with a lot of teasing from dean"

"I'm gonna grab a shower before dad gets back and hogs all the hot water." Dean informs his brother, closing the research books in front of him and walking towards the motel bathroom.

Sam nods, not bothering to look up from his laptop in his position sitting atop his bed. 

It's safe to say that the Winchester brothers have a unspoken deal, when one of them is in the shower. That is the only time the other boy has to jerk off, if needed. It isn't official, and they have never even mentioned it to one another, but whenever Sam is in the shower, he can almost always hear how loud his brother is. 

Once Dean closes and locks the bathroom door, Sam quickly opens a new tab on his screen and types 'huge cock with twink gay porn' in google. 

The younger boy may have a bit of a size kink, he'll admit that. But it's nothing he can't control. 

Right?

\---

Dean is only half way into his -typically- 20 minute shower, when he comes out of the bathroom, completely naked. For a moment, Sam is too distracted to notice, 4 fingers sunk deep inside of his hole. But when he looks up, his mouth falls open.

Sam is so turned on at this point, that he doesn't even register the fact that the video playing on his laptop is still playing... Out loud. The playback fills the room with the muscled man's words-

"That's it baby, take my cock."  
"You like it big, don't you?"  
"You ride my dick like such a little princess, I love it." 

-or the fact that his own cock was very much out, and his fingers are still deep inside of his thick ass.

"Sam?" Dean says awkwardly, trying to lift his brothers eyes up from his cock, "Samuel? Bro, your video..." 

Sam shakes his head, coming back to reality and he blushes lightly, closing the laptop, causing the noise to stop and he pulls all 4 fingers out of his aching hole.

"S-sorry... Where's your uhm- your towel?" Sam stutters, feeling his mouth growing dry. 

"Damn motel has a 'bring your own' policy." He shakes his head in annoyance. "But uh- if you wanna finish, there, bro, don't let me stop you..." 

Sam pulls the light blanket up over his lap, trying to maintain SOME decency, and shakes his head. "I-its okay..." 

"You sure?" Dean asks rhetorically, digging through his duffle bag. "Ya lil twink." 

"I am not a twink!" Sam declares defensively. "I just... Uhm... Look like one... I guess..."

Dean chuckles and nods, not believing his brother in the slightest. 

"So, what were you watching?" He asks, taking his toothbrush out of the bag, still completely nude at the end of his brothers bed, his large cock hanging soft between his muscular thighs. 

"Oh- it uhm... It was nothing." Sam lies, covering his cock with his hand through the, almost threadbare, motel blanket.

"Okay, let me see your laptop then." Dean kneels on his brother's bed, moving slowly enough to keep Sam's attention on him, and he grabs the computer from beside him, opening it and pressing play. 

"Oooh, fuuuuck- yes pound me, daddy."  
"Such a little cockslut, aren't you?"  
"Just gotta put a nice big cock in you, huh? Make you listen?"  
"You want to cum on my huge cock, little boy?" 

Dean smirks and looks up at his little brother, who's face is bright red.

"Oh, so that's why you're being so quiet right now..." Dean licks his lips slowly and closes the laptop again, setting it on the floor. "Have you ever fucked someone that big, baby brother?"

Sam shakes his head slowly, eyes locking on the cock in front of him. 

"Well, do you want to?" Dean asks, pulling his lip between his teeth and wrapping a hand around himself. 

His dick is 8.5" soft, but grows to 10.5" when it is hard. And Dean knows his cockslut little brother will love it. 

Sam looks up at his face, unsure of what he is offering. 

"You heard me, Sammy. Do you want to fuck yourself on your big brother's cock?" Dean is stroking himself to full hardness and Sam nods quickly, pulling the blanket off of himself, allowing Dean to see his baby brother's small cock, standing at a mere 5" long. 

"Come here then, little slut." 

Sam nods quickly and crawls over the bed towards his brother, his stretched hole clenching around nothing as he moves.

"D-Dean... You're so big..." Sam whispers, training a finger down his big brother's chest. 

The elder brother just smirks and wraps an arm around Sam's waist, pulling him close. 

"Come ride me, Sammy." 

He doesn't need to be told twice, Sam climbs over his brother's lap and lines up his now-solid cock before sinking slowly onto it. 

"Ohhhh fuck... D-Dean- I," He is cut off by a loud gasp as the tip of his brothers cock grazes his prostate. "Oh god... S-so big..." 

Dean moves his hands to his brothers waist, helping slowly sink down. 

"Go slow, baby boy. Don't wanna hurt your pretty little hole." He moves a large calloused hand underneath his brother, caressing the place where their bodies connect, moaning deeply. 

"Shit- oh my god.... D-Dean, what if Dad comes back and sees you f-FUCK... Fucking me?" 

Dean smirks and plants his lips on his brother's milky neck, sucking gently. "Guess he'll get a free show, huh?" 

Sam moans at that and nods his head, being sure to tip back his head a little more than necessary, so his brother can mark up his neck nice and pretty. 

"You ready, Sammy?" The older boy asks, ready to fuck inside of him. 

When he receives a nod, he clutches the taller boy's waist and lifts his hips upward gently, careful not to hurt Sam.

Sam moves his hands to Dean's shoulders to hold himself steady, groaning through his teeth. In the back of his mind, he is aware of the fact that this man is his fucking brother, but he couldn't care less right now. 

"F-fuck me, Dean. God, I love your cock." 

"Mmm, you're a noisy little thing, aren't you, baby brother?" Dean chuckles, used to the obscene noises people make while they are atop of his cock. "You want me to pound into you, Sammy?"

He doesn't even have time to answer and as Dean is picking his brother up, he lays him back down on the bed, never pulling out his cock. 

Sam writhes under him, trying to fuck back on his cock as he rearranges themselves. "P-please, Dean..." 

"Hold on, Sammy, baby. Don't worry, I'll fuck you properly in a second." He comforts his brother while he leans over, grabbing Sam's lube from the side table. 

Dean flips open the lid on the small bottle, pouring a nickel-sized amount on his brothers hole, biting his lip at the sight of how wide it is stretched for him. 

After shutting the bottle and tossing it on the floor nearby, Dean lifts his brothers legs up, holding them in position by his thighs. 

"Ready Sammy?" 

When Sam nods, he trusts into him, loving the way his face contorts in pleasure. Each thrust, pressing against the wreathing boy's prostate, from the sheer size of Dean's cock. Almost as wide as a pop can, and longer than his own forearm, pounding into Sam's hole eagerly. 

"Fuck, baby brother, I've never had anyone take me so well before." He punctuates the sentence with a particularly hard thrust, pulling a long moan from Sam's lips. "Not. Even. Girls. Sammy." 

Sam reaches up, tangling a hand in his long hair, trying to resist the need to stroke his untouched cock. 

"Oh, fuck- Dean. Man, I'm gonna cum!" He nearly shouts, biting his lip harshly.

"That's right- cum for your big brother. Let me see how much you love my cock." Dean groans, knowing his release is close, too. 

"Fuck!" Sam yells as he cums, pulling at his hair with one hand, the other pinching at his hard nipple. 

Dean moans and pulls out of his brother, jerking himself off quickly, ready to cum on his stomach when the door opens. 

"What the fuck are you doing?!" John shouts in surprise and disgust. 

"Shit, Sammy!" Dean moans, and he cums over his little brother with a final moan.

**Author's Note:**

> Thanks for reading! I might be interested in writing a part 2 for this, so let me know in the comments!  
> be sure to leave kudos if you enjoyed this!


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